AIPMT Chemistry 1998

aipmt–Past papers: 

aipmt–Past papers CHEMISTRY- UNSOLVED PAPER - 1998

SECTION – I (Total Marks : 50): 

SECTION – I (Total Marks : 50) Single Correct Answer Type There are five parts in this question. Four choices are given for each part and one of them is correct. Indicate you choice of the correct answer for each part in your answer-book writing the letter (a), (b), (c) or (d) whichever is appropriate

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01 A 5% solution of cane sugar (mol. Wt. = 342) is isotonic with 1 % solution of a substance X. The molecule weight of X is 68. 4 171.2 34.2 136.8 Problem

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Problem 02 Schottky defect in crystals is observed when Density of the crystal is increased Unequal number of cations and anions are missing from the lattice An ion leaves its normal site and occupies an interstitial site Equal number of cations and anions are missing from the lattice

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Problem 03 In DNA the complementary bases are Adenine and guanine; guanine and cytosine Uracil and adenine; cytosine and guanine Adenine and thymine; guanine and cytosine Adenine and thymine; guanine and uracil

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Problem 04 Aspirin is an acetylation product of m- Hydroxybenzoic acid o- Dihydroxybenzene o- Hydroxybenzoic acid p- Dihydroxybenzene

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Problem 05 The number of molecules of ATP produced in the lipid metabolism of a molecule of palmitic acid is 56 36 130 86

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Problem 06 Aniline is reacted with bromine water and the resulting product is treated with an aqueous solution of sodium nitrite in presence of dilute hydrochloric acid. The compound so formed is converted into a tetrafluoroborate which is subsequently heated dry. The final product is p- bromoaniline p- bromofluorobenzene 1, 3, 5-tribromobenzene 2, 4, 6-tribromofluorobenzene

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Problem 07 which one of the following esters cannot undergo Claisen self-condensation? C 6 H 5 CH 2 COOC 2 H 5 C 6 H 5 COOC 2 H 5 CH 3 -CH 2 -CH 2 -CH 2 -COOC 2 H 5 C 6 H 11 CH 2 COOC 2 H 5 .

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Problem 08 An ester (a) with molecular formula, C 9 H 10 O 2 was treated with excess, of CH 3 MgBr and the complex, so formed, was treated with H 2 SO 4 to give an olefin (b). Ozonolysis of (b) gave a ketone with molecular formula C 8 H 8 O which shows + ve iodoform test. The structure of (a) is H 3 COCH 2 COC 6 H 5 C 2 H 5 COOC 6 H 5 C 6 H 5 COOC 2 H 5 p-H 3 CO-C 6 H 4 -COCH 3

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Problem 09 Iodoform test is not given by Ethanal Ethanol 2-pentanone 3-pentanone

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Problem 10 Which one of the following compounds will be most easily attacked by an electrophile ? a. b. c. d.

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Problem 11 The vapour pressure of solvent decreased by 10 mm of mercury when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be the mole fraction of the solvent if the decrease in the vapour pressure is to be 20 mm of mercury ? 0.4 0.6 0.8 0.2

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Problem 12 The Bohr orbit radius for the hydrogen atom (n = 1) is approximately 0.530 Å. The radius for the excited state (n = 2) orbit is (in Å) 4.77 1.06 0.13 2.12

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Problem 13 The position of both, an electron and a helium atom is known within 1.0 nm. Further the momentum of the electron is known within 5.0 x 10 -26 kg ms -1 . The minimum uncertainty in the measurement of the momentum of the helium atom is 8.0 x 10 -26 kg ms -1 80 kg ms -1 50 kg ms -1 5.0 x 10 -26 kg ms -1

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Problem 14 Identify the correct statement regarding entropy At absolute zero of temperature, the entropy of all crystalline substances is taken to be zero. At absolute zero of temperature, the entropy of a perfectly crystalline substance is + ve . At absolute zero of temperature, entropy of a perfectly crystalline substance is taken to be zero. At 0 0 C. the entropy of a perfectly crystalline substance is taken to be zero.

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Problem 15 If K 1 and K 2 are the respective equilibrium constants for the two reactions, the equilibrium constant of the reaction. will be K 1 /K 2 K 1 .K 2 K 1 /(K 2 ) 3 K 2 /K 1

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Problem 16 Given the numbers: 161 cm, 0.161 cm, 0.0161 cm. The number of significant figures for the three numbers is 3, 3 and 4 respectively 3, 4 and 4 respectively 3, 4 and 5 respectively 3, 3 and 3 respectively

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Problem 17 The edge length of face centred unit cubic cells is 508 pm. If the radius of the cation is 110 pm, the radius of the anion is 144 pm 398 pm 288 pm 681 pm

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Problem 18 Activation energy of a chemical reaction can be determined by Evaluating rate constants at two different temperatures. Evaluating velocities of reaction at two different temperatures Evaluating rate constant at standard temperature Changing concentration of reactants

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Problem 19 At the critical concentration (CMC) the surfactant molecules Associate Dissociate Decompose Become completely soluble

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Problem 20 The number of anti-bonding electron pairs in O 2 2- molecular ion on the basis of molecular orbital theory is (Atomic number of O is 8) 3 2 5 4

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Problem 21 A one litre flask is of brown bromine vapour . The intensity of brown colour of vapour will not decrease appreciably on adding to the flask some Carbon tetrachloride Animal charcoal powder Pieces of marble Carbon disulphide

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Problem 22 Which one of the following pairs of substances on reaction will not evolve H 2 gas? Copper and HCl (aqueous ) Iron and stem Iron and H 2 SO 4 (aqueous) Sodium and ethyl alcohol

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Problem 23 In PO ion, the formal charge on each oxygen atom and P- O bond order respectively are -0.75, 1.25 -0.75, 1.0 -0.75, 0.6 -3, 1.25

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Problem 24 The first ionization potentials ( eV ) of Be and B respectively are 8.29, 8.29 9.32,9.32 8.29,9.32 9.32,8.29

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Problem 25 Which one of the following elements constitutes a major impurity in pig iron? Sulphur Oxygen Silicon Carbon

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Problem 26 The second order Bragg Diffraction of X-rays with λ=1.00 Å from a set of parallel planes in a metal occurs at an angle 60 0 . The distance between the scattering planes in the crystal is 2.00 Å Å 0.575 Å 1.15 Å

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Problem 27 Among the following which one is not paramagnetic ? [Atomic numbers; Be = 4, Ne = 10, As = 33, Cl = 17] Ne 2+ Be + Cl - As +

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Problem 28 One mole of an ideal gas at 300 K is expanded isothermally from an initial volume of 1 liter to 10 litres . The for this process is (R = 2 cal. Mol -1 K -1 ) 1381.1 cal. Zero 163. 7 cal 9 lit. atm

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Problem 29 Haemoglobin contains 0.334% of iron by weight. The molecular weight of haemoglobin is approximately 67200. The number of iron atoms (Atomic weight of Fe is 56) present in one molecule of haemoglobin is 4 6 3 2

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Problem 30 For the cell reaction, of an electrochemical cell, the change in Free Energy at a given temperature is function of ln (C 2 ) ln (C 2 /C 1 ) ln (C 1 ) ln (C 1 + C 2 )

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Problem 31 The total number of possible isomers for the complex compound [Cu 11 (NH 3 ) 4 ][Pt 11 Cl 4 ] are 5 6 3 4

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Problem 32 A co-ordination complex compound of cobalt has the molecular formula containing five ammonia molecules, one nitro group and two chlorine atoms for one cobalt atom. One mole of this compound produces three mole ions in an aqueous solution. On reacting this solution with excess of AgNO 3 solution, we get two moles of AgCl precipitate. The ionic formula for this complex would be [Co(NH 3 ) 5 (NO 2 )] Cl 2 [Co(NH 3 ) 5 Cl][ Cl (NO 2 )] [Co(NH 3 ) 4 (NO 2 ) Cl ](NH 3 ) Cl ] (Co(NH 3 ) 5 ][(NO 2 ) 2 Cl 2 ]

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Problem 33 Which one of the following ionic species will impart colour to an aqueous solution? Zn 2+ Cu + Ti 4+ Cr 3+

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Problem 34 In the reaction, when 1 mole of ammonia and 1 mole of O 2 are made to react to completion : All the oxygen will be consumed mole of NO will be produced mole of H 2 O is produced all the ammonia will be consumed

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Problem 35 IUPAC name of [Pt(NH 3 ) 3 (Br)(NO 2 ) Cl ] Cl is Triamminebromochloronitroplatinum (IV) chloride Triamminebromonitrochloroplatinum (IV) chloride Triamminechlorobromonitrpolatinum (IV) chloride Triamminenitrochlorobromoplatinum (IV) chloride

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Problem 36 Which one of the following elements shows maximum number of different oxidation states in its compounds? Gd La Eu Am

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Problem 37 In crystals of which one of the following ionic compounds would you expect maximum distance between centers of cations and anions? CsI CsF LiF LiI

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Problem 38 When a substance (a) reacts with water it produces a combustible gas (b) and a solution of substance (c) in water. When another substance (d) reacts with this solution of (c), it also produces the same gas (b) on warming but (d) can produce gas (b) on reaction with dilute sulphuric acid at room temperature. Susbstance (a) imparts a deep golden yellow colour to a smokeless flame of Bunsen burner. Then (a), (b), (c) and (d) respectively are Ca, H 2 , Ca(OH) 2 , Sn K, H 2 , KOH, Al Na, H 2 , NaOH , Zn CaC2, C 2 H 2 , Ca (OH) 2 , Fe

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Problem 39 Without losing its concentration ZnCl 2 solution cannot be kept in contact with Pb Al Au Ag

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Problem 40 Repeated use of which one of the following fertilizers would increase the acidity of the soil? Ammonium sulphate Superphosphate of lime Urea Potassium nitrate

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Problem 41 Reaction of with RCH 2 CH 2 OH RCHOHCH 3 RCHOHR

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Problem 42 Glucose molecule reacts with X number of molecules of phenyl-hydrazine to yield osazone . The value of X is Two One Four Three

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Problem 43 Which one of the following compounds is resistant to nucleophilic attack by hydroxyl ions ? Dimethyl ether Acetonitrile Acetamide Methyl acetate

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Problem 44 2-Bromopentane is heated with potassium ethoxide in ethanol The major product obtained is . Trans-pentene-2 Pentene-1 2-ethoxypentane cis-pentene-2

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Problem 45 Which one of the following orders is correct regarding the –1 effect of the substituents ? —NR 2 < —OR < —F —NR 2 > —OR > —F —NR 2 < —OR > —F —NR 2 > —OR < —F

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Problem 46 An organic compound containing C, H and N gave the following analysis C = 40%, H = 13.33%, N = 46.6% Its empirical formula would be CH 4 N CH 5 N C 2 H 7 N 2 C 2 H 7 N

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Problem 47 Which one of these is not compatible with arenas ? Electrophilic additions Delocalisaton of π-electrons Greater stability Resonance

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Problem 48 Which of the following compounds is not chiral ? CH 3 CHDCH 2 Cl CH 3 CH 2 CHDCl DCH 2 CH 2 CH 2 Cl CH 3 CHClCH 2 D

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Problem 49 IUPAC name of the compound is Trans-2-Chloro-3-lodo-2-Pentene Cis-2-Chloro-3-lodo-2-Pentene Trans-3-lodo-4-Chloro-3-Penetene Cis-3-lodo-4-Chloro-3-Penetene

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Problem 50 Number of neutrons in a parent nucleus X, which gives 7N14 nucleus after two successive β emissions, would be 7 6 9 8

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